module.exports = function eventdemo() {
    // 引入 events 模块
    var events = require('events');
    // 创建 eventEmitter 对象
    var eventEmitter = new events.EventEmitter();

    // 创建事件处理程序
    var connectHandler = function connected(data, next) {
        console.log('连接成功。');
        console.log(data);
        console.log(next);

        // 触发 data_received 事件 
        eventEmitter.emit('data_received');
    }

    // 绑定 connection 事件处理程序
    eventEmitter.on('connection', connectHandler);

    // 使用匿名函数绑定 data_received 事件
    eventEmitter.on('data_received', function () {
        console.log('数据接收成功。');
    });

    // 触发 connection 事件 
    eventEmitter.emit("connection", "hello", "world");

    console.log("程序执行完毕。");
}